1. Field of the Invention
This invention relates to a method for manufacturing a semiconductor device, and, in particular, to a method for manufacturing a polysilicon-gate metal oxide semiconductor integrated circuit (MOSIC).
2. Background of the Invention
A polysilicon-gate MOSIC is well known in the art. Use of polysilicon to form the gate electrode of a self-aligned MOS field effect transistor (FET), contributes to increase in the density of MOSFETs. In such a prior art MOSFET or MOSIC, the gap a (see FIG. 3) between the side edge of a polysilicon gate 2 and the side edge of a contact hole 6 or 8 in a field region 4 was required to be in the order of 2 to 3 microns. This is the minimum required for preventing the metal layer formed in the contact holes 6 and 8 for establishing an electrical contact with diffusion regions defined in a substrate, from contacting the polysilicon gate 2 to establish an undesired short circuit. This has been an impediment in further efforts to increase the density of MOSIC.